Polymers prepared from functionalized dimethoxyphenol monomers

ABSTRACT

Dimethoxyphenol-based monomers containing polymerizable functional groups such as [meth]acrylate groups are useful for the preparation of polymers, wherein one or more dimethoxyphenyl moieties are part of side chains pendant to the backbones of the polymers. The polymers thereby obtained may have different, improved properties, such as higher glass transition temperatures, thermal stability and solvent resistance, as compared to polymers based on other types of lignin-derived monomers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.62/191,551, filed Jul. 13, 2015. The disclosure of the aforementionedapplication is incorporated herein by reference in its entirety for allpurposes.

FIELD OF THE INVENTION

The present invention relates to polymerizable monomers derived from orbased on dimethoxyphenols such as syringol, polymers prepared from suchmonomers, and methods of making such polymers.

DESCRIPTION OF THE RELATED ART

To address sustainability challenges associated with petrochemicals,researchers have exploited a plethora of renewable chemicals to generatebiobased, cost-effective, and thermomechanically useful macromolecules.Lignin is one renewable resource that shows promise as a desirablealternative to petroleum feedstocks, largely due to its abundance as abyproduct of pulp and paper refining. Corresponding lignin-basedbio-oils (e.g., the volatile fraction of pyrolyzed lignin) containnumerous aromatic compounds that structurally mimic common monomers(e.g., bisphenol A and styrene) for polymer applications. The exactstructure and composition of a lignin-based bio-oil is highly variable,depending on the biomass resource, lignin type and depolymerizationroute, among other factors. In general, the native components of alllignin-based bio-oils include phenols and guaiacols (2-methoxyphenols),whereas the native components of angiosperm (hardwood, e.g., oak andmaple trees) and graminaceous (grassy, e.g., switchgrass and cornstover) bio-oils also include syringols (2,6-dimethoxyphenols).

Biobased compounds increasingly are being incorporated intothermoplastic elastomers (TPEs), pressure-sensitive adhesives, compositebinders, and drug delivery vehicles, each of which is a system thatbenefits from macromolecules prepared via controlled polymerizationtechniques. The synthesis methods, such as reversibleaddition-fragmentation chain-transfer (RAFT), anionic or atom-transferradical polymerization, among others, are desirable for facilitating thegeneration of polymers (including block copolymers) with precisemacromolecular characteristics through the control of kineticparameters. For RAFT polymerizations, important parameters include theapparent propagation rate (which describes monomer-to-polymer conversionrates) and the apparent chain-transfer coefficient (which describes theconsumption rate of chain-transfer agent and the conversion-dependentchange in polymer density). Kinetic parameters that are consistent, inaddition to controllable, also facilitate comparisons of polymerproperties due to the ease with which macromolecules of matchingend-groups, molecular weights and dispersities can be prepared.

For the above applications, properties that are among the mostindicative of material practicality are the glass transition temperature(T_(g)), degradation temperature (T_(d)), and the zero-shear viscosity.The T_(g) indicates that temperature at which a macromoleculetransitions between glassy (solid-like) and rubbery (liquid-like)behavior, and the zero-shear viscosity describes how easily a materialmay deform at a given temperature. Polymers with a T_(g) slightly above100° C. are useful for boiling-water-stable plastics, and polymers witha T_(g) well above 100° C. are useful for high-temperature applications(e.g., machine parts and asphalt components). In theory, one couldaccess polymers having T_(g)'s anywhere from 100° C. to 200° C. viabiobased monomers and controlled polymerizations. At present, however,there is a dearth of actual examples of high molecular weightmacromolecules having glass transition temperatures in the range of fromabout 135 to about 190° C.

BRIEF SUMMARY OF THE INVENTION

Various exemplary aspects of the present invention may be summarized asfollows:

Aspect 1: A polymerizable monomer, comprised of a phenyl ring, twomethoxy groups substituted on the phenyl ring, and at least onesubstituent on the phenyl ring comprised of at least one polymerizablefunctional group other than a hydroxyl group.

Aspect 2: The polymerizable monomer of Aspect 1, wherein the substituentcomprised of at least one polymerizable functional group is substitutedat position 1 of the phenyl ring and the two methoxy groups aresubstituted at the 2 and 6 positions of the phenyl ring, the 2 and 3positions of the phenyl ring, the 2 and 4 positions of the phenyl ring,the 3 and 4 positions of the phenyl ring, or the 3 and 5 positions ofthe phenyl ring.

Aspect 3: The polymerizable monomer of Aspect 1 or 2, having a structurecorresponding to formula (I):

-   -   wherein R₁ is selected from the group consisting of hydrogen,        hydroxyl, hydrocarbyl moieties and heteroatom-containing organic        moieties; and    -   wherein R₂ is the substituent comprised of at least one        polymerizable functional group

Aspect 4: The polymerizable monomer of Aspect 3, wherein R₁ is ahydrocarbyl group selected from the group consisting of alkyl groups,alkenyl groups, and allyl groups.

Aspect 5: The polymerizable monomer of Aspect 3 or 4, wherein R₁ is aheteroatom-containing organic moiety selected from the group consistingof aldehyde-containing groups, ketone-containing groups, carboxylicacid-containing groups, and hydroxyl-containing groups.

Aspect 6: The polymerizable monomer of any of Aspects 3 to 5, wherein R₁is hydrogen, methyl, ethyl, n-propyl, i-propyl, formyl, acetyl,—CH₂C(═O)CH₃, —CH₂CH₂OH, —CH₂CH₂OH, —CH₂CHO, —CH₂CH₂CHO, —C(═O)CH₂CH₃,—CO₂H, —CH₂CO₂H, —C(═O)CH(OH)CH₃, —C(═O)CH(OCH₂CH₃)C(═O)CH₃,—CH(OCH₂CH₃)C(═O)CH₃, —CH═CHCHO, —CH═CHCH₂OH, —CH═CHCO₂H, —CH═CH₂,CH═CHCH₃ or —CH₂CH═CH₂.

Aspect 7: The polymerizable monomer of Aspect 3, wherein R₁ is hydrogenor formyl (—C(O)H).

Aspect 8: The polymerizable monomer of any of Aspects 1 to 7, whereinthe at least one polymerizable functional group is an ethylenicallyunsaturated functional group.

Aspect 9: The polymerizable monomer of any of Aspects 1 to 8, whereinthe at least one polymerizable functional group is selected from thegroup consisting of [meth]acrylate, maleinate, maleate, fumarate,[meth]acrylamide, vinyl, allyl, vinyl ester and vinyl amide.

Aspect 10: The polymerizable monomer of any of Aspects 3 to 6, whereinR₂ is [meth]acrylate.

Aspect 11: The polymerizable monomer of any of Aspects 3 to 6, whereinR₁ is hydrogen or formyl and R₂ is [meth]acrylate.

Aspect 12: A polymer comprising, in polymerized form, one or morepolymerizable monomers in accordance with any of Aspects 1 to 11.

Aspect 13: The polymer of Aspect 12 additionally comprising, inpolymerized form, one or more polymerizable co-monomers other thanpolymerizable monomers comprised of a phenyl ring, two methoxy groupssubstituted on the phenyl ring, and at least one substituent on thephenyl ring comprised of at least one polymerizable functional groupother than a hydroxyl group.

Aspect 14: The polymer of Aspect 13, wherein the one or morepolymerizable co-monomers are selected from the group consisting oflignin-based monomers, styrenes, phenyl [meth]acrylates, alkyl[meth]acrylates, [meth]acrylates other than alkyl [meth]acrylates andphenyl [meth]acrylates, terephthalates, amides, amines, diamides,diamines, dichlorides, nitriles, carboxylic acids, lactones, lactams,maleates, fumarates, malonates, maleinates, vinyls, vinyl esters, vinylamides, [meth]acrylamides, thiols, dithiols, polythiols, enes, dienes,olefins, allyl monomers, azides, diazides, phosgene, carbonates,carbamates, succinates, alcohols, silanes, silicones, siloxanes, ethers,vinyl ethers, vinyl sulfides, isocyanates, epoxides, norbornenes,anhydrides and combinations thereof.

Aspect 15: The polymer of Aspect 13 or 14, wherein the polymer is ablock copolymer, random copolymer, or gradient copolymer.

Aspect 16: A method of making a polymer, comprising polymerizing one ormore polymerizable monomers in accordance with any of Aspects 1 to 11,optionally in combination with one or more polymerizable co-monomersother than polymerizable monomers in accordance with Aspect 1.

Aspect 17: The method of Aspect 16, wherein the polymerization iscarried out using reversible addition-fragmentation chain transfer(RAFT) polymerization.

Aspect 18: A method of making a polymerizable monomer in accordance withany of Aspects 1 to 11, comprising reacting a dimethoxy-substitutedphenol containing a phenolic hydroxyl group with a functionalizedreagent containing at least one polymerizable functional group otherthan a hydroxyl group and at least one functional group reactive withthe phenolic hydroxyl group.

Aspect 19: The method of Aspect 18, wherein the functionalized reagentis selected from the group consisting of anhydrides, acyl halides,alcohols, carboxylic acids, acrylamides, epoxies and vinyls and at leastone functional group reactive with the phenolic hydroxyl group.

Aspect 20: The method of Aspect 18 or 19, wherein the polymerizablemonomer is a dimethoxyphenol [meth]acrylate, the dimethoxy-substitutedphenol is a syringol, a 2,3-dimethoxyphenol, a 2,4-dimethoxyphenol, a3,4-dimethoxyphenol, or a 3,5-dimethoxyphenol and the functionalizedreagent is [meth]acrylic anhydride or [meth]acryloyl chloride.

In various other aspects of the invention, syringyl methacrylate (alsoknown as 2,6-dimethoxyphenyl methacrylate) is synthesized from syringoland subsequently polymerized using reversible addition-fragmentationchain-transfer polymerization. Homopolymers and heteropolymers (andcopolymers) prepared from syringyl methacrylate and related monomerswere found to have broadly tunable and highly controllable glasstransitions temperatures ranging from 114° C. to 205° C. and zero-shearviscosities ranging from about 0.2 kPa·s to about 17,000 kPa·s at 220°C., with consistent thermal stabilities. The tailorability of theseproperties was found to be facilitated by the controlled polymerizationkinetics of syringyl methacrylate, with the presence of two methoxygroups ortho to the methacrylate functionality surprisingly having anegligible effect on monomer reactivity (contrary to expectation).Syringol, the precursor to syringyl methacrylate, is an abundantcomponent of depolymerized hardwood (e.g., oak) and graminaceous (e.g.,switchgrass) lignins, making syringyl methacrylate and relatedsyringol-based monomers a potentially sustainable and low-cost candidatefor tailoring macromolecular properties.

The glass transition temperature for poly(syringyl methacrylate) wasfound to be greater than that reported in the literature for almost anyother amorphous polymer lacking cyclic groups in its backbone, yet themonomer is readily polymerizable, especially in comparison to otherhigh-T_(g) phenyl methacrylates such as 2,6-dimethylphenyl methacrylate(structurally similar to syringyl methacrylate, but having methyl ratherthan methoxy groups at the 2 and 6 positions of the phenyl ring).Poly(syringyl methacrylate) was confirmed to have a T_(g) approximately120° C. higher than that of poly(2-methoxyphenol methacrylate); theintroduction of a second o-methoxy group on the monomer thus results ina substantial increase in the glass transition temperature of theresulting homopolymer.

It was unexpected that thermally-stable syringol-based monomers could beobtained and successfully polymerized into useful macromolecules usingthe procedures described herein.

First, phenolic molecules with substituents at the 2- and 6-positionsgenerally form stable radicals, dimers, and/or quinones, which make themeither difficult to functionalize or radical scavengers (E. R.Altwicker, “The Chemistry of Stable Phenoxy Radicals,” Chem. Rev., Vol.67 (5), 1967, p. 475-531). These characteristics also make2,6-difunctional phenols excellent polymerization inhibitors. Indeed,butylated hydroxytoluene (2,6-di-tert-butyl-4methylphenol) is a commonantioxidant and additive used to prevent both polymer degradation andpolymerization; a number of quinones, which can be easily prepared fromsyringols among other difunctional phenols, serve similar purposes.

Second, the most similar polymer known in the literature to thesyringol-based polymers of the present invention could be considered tobe poly(2,6-dimethylphenyl methacrylate), in which similarity is definedby the monomer being a sterically hindered (2,6-disubstituted phenyl)monomer. In one of the seminal works that studied the synthesis of thismaterial (B. Yamada, S. Sugiyama, S. Mori, and T. Otsu, “Low CeilingTemperature in Radical Polymerization of 2,6-DimethylphenylMethacrylate,” J. Macromol. Sci. Chem., Vol. A15(2), 1981, p. 339-345),the authors found that the more sterically hindered the monomer, themore difficult it is to synthesize a polymer. Furthermore, the growingpolymer would begin to depolymerize during synthesis if the temperaturereached, for example, 73° C., and the thermal stability of the polymerwas low in comparison to less-substituted phenyl methacrylates. Assyringols themselves also are highly substituted (methoxy and methylgroups are both bulky), a skilled person would have likely assumed thatthe syringol-based monomers would behave similarly, eitherdepolymerizing or degrading at low temperatures during or aftersynthesis, respectively. This would explain why, before now, neithersyringol-based monomers nor other sterically hindered phenyl-basedmonomers (e.g., 2,6-di-tert-butylphenyl methacrylate) have been builtinto polymers. The examples included herein show that these assumptionsare incorrect for syringol-based monomers. Indeed, the syringol-basedmonomers may be readily synthesized and may polymerize more rapidly thananalogous less-substituted guaiacol-based monomers and the resultingpolymers are just as thermally stable with higher glass transitions thanthe guaiacol-based polymer analogues.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION

The disclosure of the following article authored by the inventors,including the Supplemental Information associated therewith, is herebyincorporated by reference in its entirety for all purposes: Holmberg etal., “Syringyl Methacrylate, a Hardwood Lignin-Based Monomer for highT_(g) Polymeric Materials,” ACS Macro Lett. 2016, 5, 574-578.

As used herein, the term “dimethoxyphenol” refers to a phenol having twomethoxy groups substituted on the aromatic ring, in addition to ahydroxyl group, wherein substituents (including hydrogen) are attachedto the other carbon atoms of the aromatic ring. The methoxy groups maybe substituted at various positions on the aromatic ring, such as the 2and 3 positions, the 3 and 5 positions or the 2 and 6 positions (withthe phenolic hydroxyl group being attached at the 1 position). As usedherein, the term “syringol” refers to a 2,6-dimethoxyphenol withdifferent moieties (including hydrogen) as substituents in the4-position of the aromatic ring. A syringol thus corresponds to acompound having the following structure:

The p-position moiety (R₁) may be, for example, hydrogen (—H); alkylgroups (including linear, branched and cyclic alkyl groups, includingC1-C6 alkyl groups such as methyl, ethyl, propyl, or butyl and isomersthereof); alkenyl and/or allyl groups (such vinyl, ethenyl, propenyl,butenyl); carbonyl-containing groups (especially aldehydes [formylgroups] and alkylformyl groups, acetyl and alkylacetyl groups, ketonesand alkylketones, carboxylic acids and alkylcarboxylic acids, etc.);hydroxyl, hydroxyalkyl, or other alcohol-containing groups (e.g.,hydroxyl, hydroxymethyl, hydroxyethyl, hydroxypropyl and the like);alkoxyl groups (e.g., methoxy, ethoxy, propoxy); and groups that containcombinations of different functional groups (e.g., ethoxy propenyl). Anyof these moieties may be attached as substituents to the aromatic ringsof other dimethoxyphenols within the scope of the present invention. Theexamples in the following Table 1 are the most commonly identifiedsyringols that are currently known to exist in depolymerized lignin.

TABLE 1 Names of Various “Syringols” R₁ syringol H 4-methyl syringol CH₃4-ethyl syringol CH₂CH₃ 4-propyl syringol CH₂CH₂CH₃ syringaldehyde CHOacetosyringone C═OCH₃ isopropiosyringone CH₂C═OCH₃ 4-(2-hydroxyethyl)syringol CH₂CH₂OH 4-(3-hydroxypropyl) syringol CH₂CH₂CH₂OH2-syringyl-1-ethanal CH₂CHO 3-syringyl-1-propanal CH₂CH₂CHO1-syringyl-1-propanone C═OCH₂CH₃ 1-syringyl-1,2-propanedione C═OC═OCH₃syringic acid COOH 2-(4-hydroxy-3,5-dimethoxyphenyl) CH₂COOH acetic acid2-hydroxy-1-syringyl-1-propanone C═OC(OH)CH₃2-ethoxy-1-syringyl-1-propanone C═OC(OCH₂CH₃)CH₃1-ethoxy-1-syringyl-2-propanone CH(OCH₂CH₃)C═OCH₃ Sinapyl aldehydeCH═CHCHO Sinapyl alcohol CH═CHCH₂OH Sinapinic acid CH═CHCOOH 4-vinylsyringol CH═CH₂ 4-propenyl syringol CH═CHCH₃ 4-allyl syringol CH₂CH═CH₂

It is also possible and sometimes desirable to modify the native R₁group and synthesize a new “syringol.” These new synthetic syringols mayinclude other moieties in the R₁ position including, but not limited to,alkyl (e.g., t-butyl), alkenyl, allyl, carbonyl, hydroxyl, hydroxyalkyl,or alkoxyl groups that are the same or different from those previouslymentioned or amines, alkylamines, imines, alkylimines, acetals,hemiacetals, acrylamides, cyanates, cyanate acids, carboxyls, ethers,carbonyls, azides, cyanates, isocyanates, nitriles, thiols,dithioesters, thioesters, thiocarbonylthios, sulfides, disulfides,sulfates, sulfoxides, phosphoryls, esters, lactones (cyclic ester),lactams, epoxies, halides (chloride, bromide, fluoride, iodide),metallocenes, hydrazines, arylamines, anhydrides, diisocyanates, alkylhalides, acid chlorides, alkynes, sulfonamides, enols, enolates,enamines, saccharides, monosaccharides, nucleotides, and/orphospholipids that are not present in any syringol obtained directlyfrom pyrolyzed lignin.

Generally, “syringols” are obtained from depolymerized hardwood lignins,in which the hardwood lignins come from biomass obtained from a plantsuch as, but are not limited to, oak, alder, chestnut, ash, aspen,balsa, beech, birch, boxwood, walnut, laurel, camphor, chestnut, cherry,dogwood, elm, eucalyptus, pear, hickory, ironwood, maple, olive, poplar,sassafras, rosewood, bamboo, coconut, locust, and willow trees, as wellas, but not limited to, grasses (e.g., switchgrass, bamboo, straw),cereal crops (e.g., barley, millet, wheat), and agricultural residues(e.g., corn stover, bagasse). Syringol molecules also can come frompetrochemical resources.

A “dimethoxyphenol-based monomer” in the context of the presentinvention is a dimethoxyphenol that has been modified to incorporate amoiety containing at least one polymerizable functionality (other than ahydroxyl group) at the phenol (—OH) position. Similarly, a“syringol-based monomer” in the context of the present invention is asyringol that has been modified to incorporate a moiety containing atleast one polymerizable functionality (other than a hydroxyl group) atthe phenol (—OH) position (the R₂ position), as shown in the followingimage (Formula (I)). Sometimes the term “syringyl” is used in place of“syringol” (as in “syringyl methacrylate”, for example). Thepolymerizable functionality, in certain embodiments of the invention, ispolymerizable through free radical mechanisms. In other embodiments,however, the polymerizable functionality is polymerizable through othermechanisms, such as anionic polymerization, cationic polymerization,condensation polymerization, ring-opening polymerization and so forth.

Polymerizable functionalities (e.g., for R₂) include, but are notlimited to, ethylenically unsaturated functionalities such asmethacrylate, acrylate, maleinate, maleate, fumarate, acrylamide,methacrylamide, vinyl, allyl, vinyl ester, and vinyl amide groups. Thesepolymerizable groups can be attached to the “syringol” ordimethoxyphenol precursors using acylation or esterification reactionsbetween the phenol (aromatic hydroxyl group) and a reactive moiety(i.e., a moiety reactive with the phenol) bearing at least onepolymerizable group (e.g., R₂). Reagents that can provide the newpolymerizable group include, but are not limited to, anhydrides (e.g.,methacrylic anhydride, acrylic anhydride, maleic anhydride), acylhalides (e.g., methacryloyl chloride, acryloyl chloride, vinyl chloride,and bromide, iodine, or salt analogues thereof), alcohols (e.g.,2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate,2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, etc.), carboxylicacids (e.g., methacrylic acid, acrylic acid, maleic acid), acrylamides(e.g., methacrylamide), epoxies (e.g., glycidyl methacrylate, glycidylacrylate), and vinyls (e.g., vinyl chloride, vinyl bromide). Otherpolymerizable functionalities may include maleic, allyl, vinyl,hemiacetal, alkenyl, acetal, imine, amine, hydroxyl (provided that themonomer contains at least one additional polymerizable functional groupother than a hydroxyl group), alkoxy, hydroxyalkyl, alkyl, alkenyl,acrylamide, cyanate ester, carboxyl, anhydride, ether, carbonyl,aldehyde, azide, cyanate, diisocyanate, isocyanate, nitrile, thiol,alkynyl, dithioesters, sulfide, sulfoxide, phosphoryl, disulfide, ester,cyclic ester, lactam (cyclic amide), sulfoxide, lactone (cyclic ester),or/and epoxy groups.

In one embodiment of the invention, a dimethoxyphenol-based monomer(e.g., a syringol-based monomer) is prepared by a method comprisingreacting a dimethoxyphenol (e.g., a syringol) containing a phenolichydroxyl group with a functionalized reagent containing at least onepolymerizable functional group other than a hydroxyl group and at leastone functional group reactive with the phenolic hydroxyl group. Forexample, the functionalized reagent may be selected from the groupconsisting of anhydrides, acyl halides, alcohols, carboxylic acids,acrylamides, epoxies, and vinyls. The polymerizable functional group maybe selected from any of the above-mentioned polymerizablefunctionalities, particularly free radical-polymerizable functionalgroups, e.g., ethylenically unsaturated groups such as [meth]acrylates.The functional group reactive with the phenolic hydroxyl group may beselected, for example, from the group consisting of anhydride groups,acyl halide groups, epoxy groups, carboxylic acid groups, ester groups,vinyl halide groups and the like. Methacrylic anhydride, acrylicanhydride, and maleic anhydride are examples of particularly preferredfunctionalized reagents. A catalyst may be present to promote thedesired reaction between the dimethoxyphenol/syringol and the functionalgroup reactive with the phenolic hydroxyl group. For example, when thefunctionalized reagent is an anhydride, a tertiary amine may be utilizedas a catalyst, typically at a concentration of from about 0.01 to about0.1 mol/mol tertiary amine/anhydride. It may be advantageous to reactthe anhydride and the dimethoxyphenol (e.g., syringol) at anapproximately 1:1 molar ratio or with the anhydride in a slight molarexcess relative to the dimethoxyphenol (e.g., the molar ratio ofanhydride:dimethoxyphenol is from about 1:1 to about 1.2:1). Aninhibitor may be present during reaction of the dimethoxyphenol and thefunctionalized reagent, to stabilize the dimethoxyphenol-based monomerthereby formed and to reduce the extent of degradation or byproductformation. Suitable inhibitors include, but are not limited to,sterically hindered alkylated phenols such as t-butyl-substitutedphenols; typically, it will be desirable for about 500 ppm to about 3000ppm of inhibitor to be present, based on the weight of thefunctionalized reagent. The reaction of dimethoxyphenol andfunctionalized reagent may be carried out in bulk or in an inert organicsolvent such as toluene or tetrahydrofuran. The reaction temperature maybe from about room temperature (25° C.) to about 100° C., for example.The reaction between the dimethoxyphenol and the functionalized reagentis allowed to proceed at the desired temperature for a time effective toachieve the desired degree of conversion of the starting materials tothe dimethoxyphenol-based monomer (typically, about 1 hour to about 100hours). The reaction product thereby obtained may then be worked up andpurified using any of the techniques known in the field of organicchemistry, including washing a solution of the reaction product in awater immiscible organic solvent with one or more volumes of water(which may be neutral, acidic and/or basic), neutralization,concentration (removal of solvent, by distillation for example),fractionation, precipitation, (re)crystallization, distillation,chromatography and the like. It will generally be advantageous to purifythe dimethoxyphenol-based monomer to a molar purity of at least 99%prior to utilizing the dimethoxyphenol-based monomer in apolymerization, although lower purities can be used if the impurity(ies)do(es) not negatively impact the desired polymerization.

In some cases, the functionalization procedure to attach thepolymerizable functional group to the dimethoxyphenol may cause achemical reaction to occur at one or more other substituents of thearomatic ring as well as at the phenolic —OH group. For example,functionalization of a “syringol” may cause a chemical reaction to occurat the R₁ position as well as at the phenolic —OH group. These reactionsmay make bifunctional, difunctional, or multifunctional monomers orchange the structure of R₁ in addition to adding the polymerizablefunctionality as R₂. These types of reactions may result in R₁containing methacrylate, acrylate, maleinate, maleate, fumarate,acrylamide, methacrylamide, vinyl ester, vinyl amide, maleic, allyl,vinyl, hemiacetal, alkenyl, acetal, imine, amine, hydroxyl,hydroxyalkyl, alkoxy, alkyl, alkenyl, alkynyl, acrylamide, cyanateester, carboxyl, ether, carbonyl, aldehyde, azide, cyanate, isocyanate,diisocyanate, nitrile, thiol, dithioesters, sulfide, sulfoxide,phosphoryl disulfide, ester, lactone (cyclic ester), sulfoxide, lactam(cyclic amide), and/or epoxy groups that may be the same as, similar to,or different from the R₁ in the original “syringol” and the same as,similar to, or different from the new R₂ group. The difunctional,bifunctional, or multifunctional monomers can be used to makecrosslinked materials and thermosets or graft and brush-like materials.Syringols and syringol-based monomers with modified R₁ groups provide aneven greater range of properties than those accessible through syringolsand syringol-based monomers with native R₁ groups.

As used herein, a dimethoxyphenol-based polymer refers to an oligomericor macromolecular molecule comprised of at least onedimethoxyphenol-based monomer unit that has been polymerized at least byreaction of the polymerizable functional group(s) present in themonomer. Similarly, a syringol-based polymer as used herein refers to anoligomeric or macromolecular molecule comprised of at least onesyringol-based monomer unit that has been polymerized minimally at theR₂ position (i.e., by reaction of the polymerizable functionality). Thesyringol-based monomer that comprises the syringol-based polymer alsomay have polymerized at the R₁ position in addition to the R₂ position.The homopolymerization of a syringol-based monomer corresponding toFormula (I) to provide a syringol-based polymer through reaction of apolymerizable functional group in R₂ may be schematically represented asfollows (the substituent R₁, as previously mentioned, may alsoparticipate in the polymerization, if it contains a polymerizablefunctional group):

Dimethoxyphenol-based polymers in accordance with the present inventionare not particularly limited with respect to their molecular weights ortheir geometry. For example, the dimethoxyphenol-based polymer may beeither relatively low in molecular weight (oligomeric) or relativelyhigh in molecular weight. The number average molecular weight of thedimethoxyphenol-based polymer may range from about 1000 daltons to about5,000,000 daltons or even higher, for instance. The dispersity of thedimethoxyphenol-based polymer may be relatively low (e.g., less than1.5, for example) or relatively high (e.g., 1.5 or greater). Thedimethoxyphenol-based polymer may be, for example, linear, branched oreven cross-linked in structure, depending upon the polymerizationconditions, initiators and monomers used. If the dimethoxyphenol-basedpolymer is a copolymer or heteropolymer, the copolymer may be a blockcopolymer, a random (statistical) copolymer, gradient or taperedcopolymer or the like. The dimethoxyphenol-based polymer may, in apreferred embodiment, be a thermoplastic, but may in another embodimentbe a thermoset. The dimethoxyphenol-based monomers of the presentinvention also are useful in the preparation of thermoplasticelastomers, in particular thermoplastic elastomers which are blockcopolymers in which one or more blocks are blocks of one or moredimethoxyphenol-based monomers providing a “hard” polymerized segmenthaving a relatively high T_(g) (e.g., a T_(g) of at least 100° C.) andone or more blocks are blocks of a monomer or mixture of monomersproviding a “soft” polymerized segment having a relatively low T_(g)(e.g., a T_(g) of less than 0° C.).

Dimethoxyphenol-based polymers in accordance with the present inventionmay be synthesized by any number of polymerization techniques including,but not limited to, free-radical polymerization, reversibleaddition-fragmentation chain-transfer (RAFT) polymerization,ring-opening [metathesis] polymerization (RO[M]P), step-growthpolymerization, cationic polymerization, anionic polymerization,coordination polymerization, condensation polymerization, emulsionpolymerization, Ziegler-Natta polymerization, metallocenepolymerization, group-transfer polymerization, living radicalpolymerization, reversible-deactivation radical polymerization,atom-transfer radical polymerization (ATRP), stable free radicalpolymerization (SFRP), TEMPO polymerization, cobalt-mediated radicalpolymerization, nitroxide mediated radical polymerization (NMP),catalytic chain-transfer polymerization, iniferter polymerization,iodine-transfer polymerization (ITP), selenium-centered radical-mediatedpolymerization, telluride-mediated polymerization, stibine-mediatedpolymerization, cationic ring-opening polymerization, and/orcatalyst-transfer polycondensation.

In a particular preferred embodiment, reversible addition-fragmentationchain-transfer (RAFT) polymerization is employed to prepare adimethoxyphenol-based polymer in accordance with the present invention.A dimethoxyphenol-based polymer may be prepared by a method comprisingpolymerizing at least one dimethoxyphenol-based monomer via reversibleaddition-fragmentation chain-transfer polymerization (RAFT), in thepresence of a free radical initiator and a chain transfer agent, to formthe dimethoxyphenol-based polymer. One or more co-monomers mayoptionally also be polymerized, either together as a mixture with thedimethoxyphenol-based monomer(s) or separately (sequentially orstep-wise). Reversible Addition-Fragmentation chain Transfer or RAFTpolymerization is one of several kinds of reversible-deactivationradical polymerizations. It makes use of a chain transfer agent, such asa thiocarbonylthio compound (e.g., a dithioester, a thiocarbamate or axanthate, such as 2-cyano-2-propyl benzodithioate), to afford controlover the generated molecular weight and polydispersity during afree-radical polymerization. The chain transfer agent mediates thepolymerization of the dimethoxyphenol-based monomer(s) and optionalco-monomers via a reversible chain-transfer process. The free radicalinitiator may be, for example, an azo compound such as2,2′-azobisisobutyronitrile (AIBN) or 4,4′-azobis(4-cyanovaleric acid)(ACVA). The polymerization may be carried out in an organic solvent ormixture of organic solvents, such as anisole, typically at temperaturesof from about 40° C. to about 120° C., or alternatively with no solvent(bulk). The polymerization also can be carried out as an emulsion-typepolymerization wherein one or more emulsification agents and a solvent(e.g., water) are used. Typical for RAFT polymerizations, 0.02 to 0.4moles of initiator may be used for each mole of chain transfer agent;the moles of chain transfer agent relative to the number of monomer(s)depends upon the target molecular weight and the monomer-to-polymerconversion. As with other controlled radical polymerization techniques,RAFT polymerizations can be performed with conditions to favor lowdispersity (narrow molecular weight distribution) and a pre-chosenmolecular weight. RAFT polymerization can be used to design polymers ofcomplex architectures, such as linear block copolymers, comb-like, star,brush polymers, dendrimers and cross-linked networks.

The dimethoxyphenol-based polymer may comprise polymerized units ofeither a single chemically distinct dimethoxyphenol-based monomer (i.e.,a homopolymer), a mixture of chemically distinct dimethoxyphenol-basedmonomers (to provide a copolymer), a mixture of one or moredimethoxyphenol-based monomers and one or more other lignin-basedmonomers such as guaiacol-based monomers (to provide a copolymer), or amixture of one or more dimethoxyphenol-based monomers and one or more ofany other type of polymerizable monomer (to provide a copolymer).Possible comonomers are those that can react under the samepolymerization conditions as the dimethoxyphenol-based monomer(s). Suchcomonomers include, but are not limited to:

-   a). other lignin-based monomers (2-methoxyphenol and phenol    derivatives with varying 4-position moieties) with similar    structures and functionalities as the dimethoxyphenol-based    monomers;-   b). styrenes (styrene, 4-bromostyrene, 4-fluorostyrene, etc.);    alkylstyrenes (4-methylstyrene, 2-methylstyrene,    2,4-dimethylstyrene, 4-ethylstyrene, benzhydrylstyrene, etc.);-   c). phenyl [meth]acrylates with any number and position of    substituents and especially those also derived or obtained from    lignin (e.g., phenyl [meth]acrylate, 2-methylphenyl [meth]acrylate,    4-ethylphenyl [meth]acrylate, 4-methylphenyl [meth]acrylate,    4-propylphenyl [meth]acrylate, guaiacol [meth]acrylate, creosol    [meth]acrylate, 4-ethylphenyl [meth]acrylate, 4-propylguaiacyl    [meth]acrylate, eugenol [meth]acrylate, vanillin [meth]acrylate,    trimethoxysilylpropyl [meth]acrylate, and the like);-   d). alkyl [meth]acrylates with alkyl chain lengths anywhere from 1    to 36 carbon atoms and any number of unsaturated bonds and    especially those that are derived or obtained from biobased    resources (e.g., methyl [meth]acrylate, ethyl [methyl]acrylate,    propyl [meth]acrylate, butyl [meth]acrylate, lauryl [meth]acrylate,    palmitic [meth]acrylate, stearic [meth]acrylate, oleic    [meth]acrylate, linoleic [meth]acrylate, and the like);-   e). other types of [meth]acrylates (e.g., [meth]acrylic acid,    perfluorooctyl [meth]acrylates, hydroxymethyl [meth]acrylate,    hydroxyethyl [meth]acrylates, poly(oligo-ethylene glycol)    [meth]acrylate, 3-sulfopropyl [meth]acrylate potassium salt, and the    like);-   f). terephthalates (e.g., polyethylene terephthalate, dimethyl    terephthalate, butylene terephthalate, trimethylene terephthalate,    dioctyl terephthalate, cyclohexylenedimethylene terephthalate,    terephthalic acid, terephthaloyl chloride, and the like);-   g). amides, amines, diamides, and diamines (e.g.,    hexamethylenediamine, diaminohexane, ethylenediamine,    para-phenylenediamine, 4,4′-oxydianiline, putrescine, tetramethylene    diamine, 2-methylpentamethylene diamine, trimethyl hexamethylene    diamine, xylylene diamine, 1,5-pentadiamine, 11-aminoundecanoic    acid, aminolauric acid, bis[para-aminocyclohexyl] methane,    diethyltoluenediamine, dimethylthiotoluenediamine, triethanolamine,    and the like);-   h). dichlorides (e.g., hexanedioyl dichloride);-   i). nitriles (e.g., acrylonitrile, 2-propenenitrile,    methacrylonitrile, 2,6-dichlorobenzonitrile,    pentachlorobenzonitrile);-   j). carboxylic acids, including monocarboxylic acids, dicarboxylic    acids and polycarboxylic acids (e.g., adipic acid, sebacic acid,    terephthalic acid, isophthalic acid, dodecanedoic acid,    4-hydroxybenzoic acid, 6-hydroxynaphthalene-2-carboxylic acid, and    the like);-   k). lactones and lactone analogues (e.g., acetolactone,    propiolactone, butyrolactone, valerolactone, caprolactone,    dodecalactone, butenolide, macrolide, cardenolide, bufadienolide,    lactide, cyclopentadenolide, coumarin, carvomenthide, menthide,    tulipalin A, and the like),-   l). lactams (e.g., caprolactam, laurolactam, vinylcaprolactam, and    the like);-   m). maleates, malonates, and maleinates (e.g., dioctyl maleate,    maleic acid, dimethyl maleate, maleic anhydride, diallyl maleate,    diethyl allylmalonate) and associated isomers, such as fumarates;-   n). vinyls (e.g., vinyl chloride, vinyl bromide, vinyl fluoride,    4-vinyl-styrene, ethylene, vinyl acetylene, vinyl naphthalene,    vinylpyridine, vinylformamide, and the like);-   o). vinyl esters (e.g., vinyl acetate, vinyl benzoate, vinyl    4-tert-butylbenzoate, vinyl chloroformate, vinyl cinnamate, vinyl    decanoate, vinyl nenodecanoate, vinyl nenononanoate, vinyl pivalate,    vinyl propionate, vinyl stearate, vinyl trifluoroacetate, vinyl    valerate, and the like);-   p). vinyl amides (e.g., N-methyl-N-vinylacetamide, vinylformamide,    vinylacetoamide, vinyl amide, and the like);-   q). [meth]acrylamides (e.g., alkyl [meth]acrylamides, butyl    [meth]acrylamide, diacetone [meth]acrylamide, diethyl    [meth]acrylamide, diethyl [meth]acrylamide, ethyl [meth]acrylamide,    hexamethylenebis[meth]acrylamide, hydroxymethy[meth]acrylamide,    hydroxyethyl [meth]acrylamide, isobutoxymethyl [meth]acrylamide,    isopropyl [meth]acrylamide, [meth]acrylamide, phenyl    [meth]acrylamide, triphenylmethyl [meth]acrylamide, and the like);-   r). thiols, dithiols, and polythiols (e.g., butanedithiol,    benzenedithiol, biphenyldithiol, benzenetrithiol, decanedithiol,    dithiothreitol, dithioerythritol, dimercaptonaphthalene,    ethanedithiol, hexanedithiol, octanedithiol, propanedithiol,    pentanedithiol, thiobisbenzenethiol, and the like);-   s). enes, dienes, and olefins (e.g., terpenes, sesquiterpenes,    ethylene, propene, butylene, isoprene, acetylene, myrcene, humulene,    caryophyllene, farnesene, limonene, methylpentene, ethylene,    propylene, butadiene, decalene, tetrafluoroethylene,    hexafluoropropylene, pinene, chloroprene, acetylene, and the like);-   t). allyl monomers (e.g., allyl acetate, allyl acetoacetate, allyl    alcohol, allylamine hydrochloride, allyl benzyl ether, allyl    2-bromo-2-methylpropionate, allyl butyl ether, allyl chloroacetate,    allyl cyanide, allyl cyanoacetate, allyl ether, allyl ethyl ether,    allyl methyl carbonate, allyl methyl sulfone, allyloxybenzaldehyde,    allyloxyethanol, allyoxy propanediol, allyl phenyl ether,    allylphosphonic acid monoammonium salt, allyl trifuloroacetate,    tert-butyl allyl carbamate, butyne, diallyl carbonate,    methylsulfonyl propyne, propyne, trimethylolpropane [di]allyl ether,    and the like, including the [meth]allyl analogues thereof);-   u). azides and diazides (ethynylene diazide, glycidyl azide, etc.);-   v). phosgene;-   w). carbonates, including cyclic carbonates;-   x). carbamates;-   y). succinates;-   z). alcohols, including diols and polyols (e.g.,    4-amino-4-3-hydroxypropyl-1,7-heptanediol, benzenedimethanol,    biphenyldimethanol, bis-hydroxymethyl-butyric acid, dihydrobenzoic    acid, propanediol, cyclohexanediol, cyclopentanediol,    dihydroxybenzophenone, dihydroxyacetophenone, dihydroxynaphthalene,    butanediol, catechol, hexanediol, hexanetriol, hydrobenzoin,    hydroquinone bis-2-hydroxyethyl ether,    2-hydroxymethyl-1,3-propanediol, pentanediol,    phenyl-1,2-propanediol, ethylene glycol, pentaerythritol, glycerol,    trimethylolpropane, and the like);-   aa). silanes, silicones, and siloxanes (e.g.,    dimethyldichlorosilane, silatrane glycol,    tetramethyl-tetravinylcyclotetrasiloxane, and the like);-   bb). ethers and vinyl ethers (e.g., vinyl ether, [di]glycidyl ether,    butanediol [di]vinyl ether, butyl vinyl ether, chlorethyl vinyl    ether, cyclohexyl vinyl ether, dodecyl vinyl ether, diethyl vinyl    orthoformate, diethylene glycol [di]vinyl ether, phenyl vinyl ether,    propyl vinyl ether, isobutyl vinyl ether, ethyl vinyl ether,    ethylhexyl vinyl ether, ethylene glycol vinyl ether, and the like);-   cc). vinyl sulfides (e.g., vinyl sulfide, phenyl vinyl sulfide,    4-chlorophenyl vinyl sulfide, bromphenyl vinyl sulfide, ethyl vinyl    sulfide, and the like);-   dd). isocyanates, including diisocyanates and polyisocyanates (e.g.,    diisocyanatobutane, diisocyanatododecane, diisocyanatooctane,    hexamethylene diisocyanate, cyclohexylene diisocyanate, phenylene    diisocyanate, tolylene diisocyanate, toluene diisocyanate, methylene    diphenyl diisocyanate, isophorone diisocyanate, and the like);-   ee). epoxides (e.g., ethylene oxide, allyl glycidyl ether, butadiene    diepoxide, butanediol diglycidyl ether, butyl glycidyl ether,    tert-butyl glycidyl ether, chlorophenyl glycidyl ether, cyclohexene    oxide, cyclopentene oxide, dicyclopetadiene dioxide, dieldrin,    diepoxycyclooctane, diepoxyoctane,    N,N-diglycidyl-4-glycidyloxyaniline, epoxybutane, epoxybutene,    epoxydodecane, epoxyhexane, epoxyhexene, epoxynorbornane,    epoxyoctane, epoxypentane, epoxy-phenoxypropane, epoxypropyl    benzene, epoxypropyl phthalimide, epoxytetradecane, ethylhexyl    glycidyl ether, furfuryl glycidyl ether, glycidyl 4-methoxyphenyl    ether, glycidyl methylphenyl ether, methyl vinyloxirane, pinene    oxide, propylene oxide, resorcinol diglycidyl ether, stilbene oxide,    styrene oxide, and the like);-   ff). norbornenes (e.g., dicyclopentadiene, norbornene,    bicycloheptadiene, and the like); and-   gg). anhydrides (e.g., [meth]acrylic anhydride, maleic anhydride,    citraconic anhydride, crotonic anhydride, itaconic anhydride,    methylglutaric anhydride, methylphthalic anhydride, methylsuccinic    anhydride, naphthalic anhydride, phenylglutaric anhydride,    phenylmaleic anhydride, and the like);    as well as combinations or mixtures of any two or more of the    above-mentioned co-monomers.

The dimethoxyphenol-based polymer may be comprised, in variousembodiments of the invention, of at least 1%, at least 5%, at least 10%,at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, atleast 70%, at least 80%, at least 90%, at least 95%, or at least 99% byweight or 100% by weight of dimethoxyphenol-based monomer(s) inpolymerized form. The balance of the dimethoxyphenol-based polymer maybe comprised of one or more of the above-mentioned co-monomers, inpolymerized form, as well as initiator moieties and/or crosslinkermoieties (to be extent initiators and/or crosslinking agents are used inthe preparation of the dimethoxyphenol-based polymer and end up beingincorporated into the dimethoxyphenol-based polymer as a result of thepolymerization).

The term [meth]acrylates or [meth]acrylamides, as used herein, means themonomer can be either an acrylate or methacrylate or acrylamide ormethacrylamide. Preferred co-monomers, in certain embodiments of theinvention, include those capable of providing copolymers which areglassy materials at room temperature (e.g., styrene and methyl[meth]acrylate) and/or other monomers that can be derived from lignin orother biomass materials (e.g., vanillin [meth]acrylate and otherguaiacol [meth]acrylates).

The dimethoxyphenol-based polymer may also be grafted to or grafted fromparticles, nanoparticles, and/or surfaces including, but not limited to,linoleum, granite, gold, concrete, silica, silicon dioxide,poly(dimethylsiloxane), poly(norbornene)s, poly(carbonate)s, graphene,graphite, diamond, garnet, ruby, emerald, topaz, talc, glass, zinc,steel, asphalt, ceramics, porcelain, tin, aluminum, foil, cloth, cotton,cellulosic fibers, lignin fibers, tetrafluoroethylene polymers,polyimides, quartz, nylon, silk, rayon, carbon nanotubes, nanowires,clay, and other organic or inorganic surfaces of varying roughness,flexibility, strength, and size.

The dimethoxyphenol-based polymer may also be a bulk or compositematerial. Many different nanoparticles and nanofibers may be blendedinto a dimethoxyphenol-based polymer before, during or afterpolymerization to impart different or enhanced properties to the productmaterial. Nanoparticles and nanofibers of any of the above-mentionedtypes of materials or substances may be utilized as media from which, orto which, a dimethoxyphenol-based polymer may be synthesized orattached/grafted.

Possible applications for the dimethoxyphenol-based monomers andpolymers of the present invention are numerous, as they can be used asmodifiers for nearly any other existing plastic or composite material.Such uses and potential applications include, but are not limited to,cosmetics, personal health and beauty, food storage and processing,pharmaceuticals, energy transportation and storage, water purification,insulation, automotive parts, windows, housing, water treatment,paper-making, waste treatment, recycling, containers, membranes, batteryand fuel-cell parts, aircraft equipment and parts, medical devicecoatings, sterile medical equipment casing, skin grafts, clothing, inks,resins for 3D (or normal) printing, viscosity controllers, foodadditives, preservatives, antioxidants, packaging, glasses, bottles,cups (disposable, washable, and/or reusable plastics), cutlery, opticalcoatings, electronics casings, sporting equipment, shoes, fasteners(zip-ties, buttons, tacks), paint, car paint, decorations, linoleum,counter tops, kitchen appliances, dampeners, carbonator coatings,gas-tank liners, toys, building blocks, microwave-safe or oven-safecontainers and cookware, writing utensils, gaskets, gears, carpets,paneling, flooring, wood alternatives, carpentry equipment, grinders,razors, solar devices, glasses coatings, glasses frames, lenses, compactdiscs, lithographic masks, self-healing materials, rocket parts, spacevehicle or interstellar vehicle parts, UV insulators, radiationshielding, satellite parts, impact-resistance coatings, bullet-proofvests and windows, space suit masks, robot parts, prosthetics, contactlenses, structural elements and binders in buildings, camera parts,cuvettes, mosquito nets, fishing line and nets, boat parts and coatings,implants, coatings for wearable electronics, high-temperature resins,Kevlar® polyimide alternatives, surfactants, lubricants, faux leatherand fabric, fire-fighter protective equipment, cookware coatings,corrosion-resistant coatings, pipes, manifolds, medical instruments andinstrument trays, electrical connectors, sensors, analytical instrumentparts, semiconductor wafer handling components, components and seals forpumps, components and seals for compressors, bearings, bushings,cleaning pads, heat shields, engine components and seals, hoses, enginehousing, valves, solenoids, latexes, nylons, aerospace parts, chemicalprocessing and transportation devices, subterranean vehicles, [deep-sea]submersibles, naval equipment, bullet or missile casings, weaponry andammo, firearms, hunting equipment, archery equipment, musical equipment,guitar strings and cases, seals, caulks, benches and seating, furnitureand furniture coatings, tables, vibration dampeners, expansion joints,o-rings, custom-shaped parts, stock rods and sheets, emergency responderkits, flame-retardant coatings, snow-mobiles, skis, snowboards,snow-shoes, winter-wear, umbrella parts, rain jackets, protectiveclothing, masks, rollerblade or roller-skate parts, bicycle parts,wear-resistant coatings, color binders, street signs, vehicle bumpers,fluid-handling parts, sidewalks, driveways, pavement, alternatives forceramics, train parts, anti-static coating, substrates for circuitry,pads, stoppers, vacuum and vacuum-cleaner parts, wire and cable tapes,pressure-sensitive adhesives, transformer and capacitor parts andinsulation, shims, machinable parts, business equipment, nets, sockets,contractors, heat deflectors, radiation filters or dampeners,moisture-resistant coatings, wind turbine blades and parts, containersfor nuclear waste storage and transportation, rollers, pressure discs,pistons, filler materials, connectors, medical tubing, syringes,catheter parts, pace-makers, implantable devices, belting, mesh,filters, sutures, medical leads, window coverings (e.g., drapes andblinds), brushes, bridge parts, cords, cables, liners, bags, pottery,washer and dryer parts, dishwasher parts, saw blades, sanders, brakes,stovetops, countertops, flooring, shingles, and polar explorationequipment.

Applications that are likely to benefit the most fromdimethoxyphenol-based monomers and polymers in accordance with thepresent invention are those that require stability at temperatures nearor above 100° C.; corrosion, solvent and/or abrasion resistance; highstrengths; and optical characteristics (such as clarity). However, thedimethoxyphenol-based monomers are also useful for modulating/enhancingproperties of materials at use temperatures below 100° C. The monomersand polymers are especially suitable for use in the aerospace, business,machining, transportation, chemical, construction, emergency-response,defense, consumer products, and medical industries. For example, medicalequipment or devices often need to be sterilized at high temperaturesand extreme pressures, so a strong polymer is desirable that will notwarp under extreme conditions. Deep-sea or space explorers, emergencyresponders, and soldiers may encounter similarly harsh environments, sotheir vessels, protective gear, and equipment all must be reliable,protective, and preferably light-weight (all characteristics availablethrough the incorporation of dimethoxyphenol-based monomers intopolymers). The high T_(g)'s of polymers produced from these monomersalso make the polymers suitable for replacing metal components in anumber of machine parts, such as in engines. The transportation industryneeds light-weight and high-T_(g) materials, such as thedimethoxyphenol-based plastics of the present invention, to reduce thefuel load. Aerospace applications and space suits also requirelight-weight, strong, impact- or abrasion-resistant, and heat- and/orradiation-resistant/shielding materials to withstand impact from spacedebris and landing, harsh conditions of extraterrestrial terrains, hightemperatures from re-entry, radiation from the sun, and so on;dimethoxyphenol-based monomers are capable of imparting thesecharacteristics into materials already use by the aerospace industry aswell as new plastics. The solvent resistance of thedimethoxyphenol-based monomers, when polymerized, can also benefit thechemical and nuclear industries, as coatings and plastics comprised ofsuch monomers may eliminate or reduce corrosion of related equipment,piping, reactors, and storage tanks.

Within this specification, embodiments have been described in a waywhich enables a clear and concise specification to be written, but it isintended and will be appreciated that embodiments may be variouslycombined or separated without departing from the invention. For example,it will be appreciated that all preferred features described herein areapplicable to all aspects of the invention described herein.

In some embodiments, the invention herein can be construed as excludingany element or process step that does not materially affect the basicand novel characteristics of the composition or process. Additionally,in some embodiments, the invention can be construed as excluding anyelement or process step not specified herein.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

EXAMPLES

Synthesis and Purification of Syringyl Methacrylate

Syringol (99%, Fisher Scientific, used as received) was acylated with1.02 molar equivalents of methacrylic anhydride (94%, inhibited with2000 ppm Topanol® A, Sigma-Aldrich, used as received) using catalyticamounts of 4-dimethylaminopyridine (DMAP, >99%, Sigma-Aldrich,recrystallized from toluene), a reaction temperature of 60° C., andreaction times between 24 h and 72 h. Syringol-to-Syringol Methacrylateconversions of >60 mol-% were achieved at higher DMAP contents (i.e.,0.06 mol/mol DMAP/methacrylic anhydride). After washing the syringylmethacrylate product in dichloromethane with a saturated sodiumbicarbonate solution, 1.0 M NaOH, 0.5 M NaOH, 1.0 M HCI, and deionizedwater and then concentrating the product by rotary evaporation, thesyringyl methacrylate was fractionated to high purity using aheat-decant-cool cycle in either hexanes or petroleum ether. Themonomer/hydrocarbon mixture was heated to reflux while stirring andsubsequently decanted into a new flask, partially separating thesyringyl methacrylate from insoluble viscous orange byproducts. Uponcooling, syringyl methacrylate phase-separated from the supernatant.This procedure was repeated with the syringyl methacrylate/hexanes (orpetroleum ether) mixture until the phase-separating syringylmethacrylate layer vitrified at room temperature, at which point theproduct was collected by Buchner filtration (7 wt-% yield, >98 mol-%purity or >99 mol-% if recrystallized once more from ethanol).Alternatively, the washed and concentrated syringyl methacrylate waspurified by automated column chromatography (Silica gel, stepped elutionof 1:9 [3 column volumes] to 2:8 [8 column volumes] v/v ethyl acetate inhexanes, >98 mol-% purity) and then recrystallized once from ethanol(>99 mol-% purity). The identity of the product as syringyl methacrylatewas confirmed by ¹H NMR: ¹H NMR δ ppm (CDCl₃, 600 MHz): 7.14 (1H, dd,J=12 Hz, 12 Hz), 6.63 (2H, d, J=12 Hz), 6.40 (1H, q, J=1.2 Hz), 5.76(1H, q, J=1.5 Hz), 3.82 (6H, s), 2.09 (3H, dd, J=1.2 Hz, 1.4 Hz).

Synthesis and Characterization of Poly(syringyl methacrylate) andHeteropolymers Containing Syringyl Methacrylate

Polymers were synthesized and purified following the proceduresdescribed in Holmberg et al., “A Facile Method for Generating DesignerBlock Copolymers from Functionalized Lignin Model Compounds.” ACSSustainable Chem. Eng. 2014, 2(4), 569-573 and Holmberg et al., “RAFTPolymerization and Associated Reactivity Ratios ofMethacrylate-Functionalized Mixed Bio-oil Constituents. Polym. Chem.2015, 6(31), 5728-5739. 2-Cyano-2-propyl benzodithioate (CPB) was usedas the chain transfer agent and 2,2′-azobisisobuyronitrile (AIBN) wasused as the free radical initiator. The components of the heteropolymersincluded one or more of the following in addition to syringylmethacrylate (SM): 4-ethylguaiacyl methacrylate (EM,4-ethyl-2-methoxyphenyl methacrylate), vanillin methacrylate (VM,4-formyl-2-methoxyphenyl methacrylate), and/or creosyl methacrylate (CM,4-methyl-2-methoxyphenyl methacrylate).

Reaction conditions and size-exclusion chromatography (SEC) data for thehomopolymers and heteropolymers are reported in Table S1. Note:macromolecular characterization equipment details are provided asfootnotes to the table. Monomer compositions, monomer-to-polymerconversions (x), and cumulative polymer compositions were determinedusing a method described in the literature (Holmberg et al., RAFTPolymerization and Associated Reactivity Ratios ofMethacrylate-Functionalized Mixed Bio-Oil Constituents. Polym. Chem.2015, 6(31), 5728-5739), the vinyl peaks for SM listed above (6.40 ppmand 5.76 ppm), and the polymer peaks (fit using MestReNova Software)indicated below. Spectra were analyzed in triplicate to determine the95% confidence in the composition, conversion, and tacticitymeasurements.

-   Poly(syringyl methacrylate) [PSM]: NMR δ ppm (CDCl₃, 600 MHz):    7.18-6.79 (1H, br), 6.67-6.14 (2H, br), 3.94-3.30 (6H, br),    3.30-1.35 (5H, many br). Non-ambient temperature (58° C.) ¹H NMR    data (CDCl₃ with 5 wt-% trifluoroacetic anhydride, 400 MHz) were    utilized for tacticity estimates. The α-methyl protons (1.90-1.45    ppm) were split into broad peaks representative of triads with    approximate chemical shifts of 1.76 ppm (mm), 1.69 (mr and rm), and    1.64 ppm (rr), which were used to estimate tacticity. These triad    peaks were assumed to be located in the same order as the analogous    triad protons in poly(methyl methacrylate) and poly(phenyl    methacrylate), in which mm is further downfield and rr is further    upfield relative to the single mr/rm peak. The fractions of racemo    diads (f_(r)) of 0.90±0.05 and syndiotactic triads (f_(rr)) of    0.85±0.09 for PSM-21 are greater than the f of ˜0.75 (and f_(r) of    ˜0.60) reported for the softwood polymers (Holmberg et al., Softwood    Lignin-Based Methacrylate Polymers with Tunable Thermal and    Viscoelastic Properties. Macromolecules 2016, 49(4), 1286-1295),    which are considered atactic.-   Poly(4-ethylguaiacyl methacrylate-co-syringyl methacrylate) [P(ES)]:    ¹H NMR δ ppm (CDCl₃, 600 MHz): 7.15-6.79 (1H/EM+1H/SM, br),    6.79-6.24 (2H/EM+2H/SM, 3 br), 3.94-3.30 (3H/EM+6H/SM, br),    3.30-1.24 (5H/EM+5H/SM, many br), 1.24-1.00 (3H/EM, br). Polymer    composition was determined via the characteristic EM peak at    1.24-1.00 ppm. The area of the peak was referenced to the area of    the aromatic proton peaks (7.15-6.79 ppm and 6.79-6.24 ppm) and the    methoxy proton peak (3.94-3.30 ppm) to estimate error. Monomer feed    composition (mol/mol): f_(EM) =0.951±0.003, f_(SM)=0.049±0.003.    Polymer composition (mol/mol): F_(EM)=0.95±0.02, F_(SM)=0.05±0.02.-   Poly(creosyl methacrylate-co-4-ethylguaiacyl    methacrylate-co-syringyl methacrylate) [P(CES)]: ¹H NMR δ ppm    (CDCl₃, 600 MHz): 7.15-6.81 (1H/CM+1H/EM+1H/SM, br), 6.81-6.52    (2H/CM+2H/EM, 2 br), 6.52-6.30 (2H/SM, br), 3.87-3.30    (3H/CM+3H/EM+6H/SM, br), 3.30-1.27 (5H/CM+5H/EM+5H/SM, many br),    1.24-1.00 (3H/EM, br). Polymer composition was determined using the    characteristic EM peak at 1.24-1.00 ppm and the characteristic SM    peak at 6.52-6.30 ppm. The areas of these peaks were referenced to    the area of the aromatic proton peaks (7.15-6.81 ppm and 6.81-6.30    ppm) and the methoxy proton peak (3.87-3.30 ppm) to estimate error.    Monomer feed composition (mol/mol): f_(CM)=0.191±0.003,    f_(EM)=0.339±0.004, f_(SM)=0.469±0.004. Polymer composition    (mol/mol): F_(CM)=0.16±0.03, F_(EM)=0.36±0.03, F_(SM)=0.48±0.02.-   Poly(vanillin methacrylate-co-4-ethylguaiacyl    methacrylate-co-syringyl methacrylate) [P(VES)]: ¹H NMR δ ppm    (CDCl₃, 600 MHz): 9.94-9.44 (1H/VM, br), 7.45-7.18 (3H/VM, br),    7.18-6.79 (1H/EM+1H/SM, br), 6.75-6.30 (2H/EM+2H/SM, 2 br),    3.82-3.30 (3H/VM+3H/EM+6H/SM, br), 3.301.24 (5H/VM+5H/EM+5H/SM, many    br), 1.24-1.00 (3H/EM, br). Polymer composition was determined using    the characteristic EM peak at 1.24-1.00 ppm and the characteristic    VM peaks at 9.94-9.44 ppm and 7.45-7.18 ppm. The areas of these    peaks were referenced to the area of the aromatic proton peaks    (7.48-6.30 ppm) and the methoxy proton peak (3.82-3.30 ppm) to    estimate error. Monomer feed composition (mol/mol):    f_(VM)=0.226±0.007, f_(EM)=0.227±0.003, f_(SM) =0.548±0.007. Polymer    composition (mol/mol): F_(VM)=0.24±0.02, F_(EM)=0.23±0.01,    F_(SM)=0.53±0.02.

TABLE S1 Polymerization conditions^(a) and characteristics of polymerscontaining SM segments [M]₀/[C]₀ ^(b) [M]₀/[S]^(b) t x M_(n,calc) ^(c)M_(n,RI) ^(d) M_(n,LS), M_(w,LS) ^(e) T_(g) (mol/mol) (wt/wt) (h)(mol/mol) (kDa) (kDa) (kDa) Ð^(d,f) (° C.) PSM-24 219 0.94  3.3^(g) 0.5329 24 — 1.74 205 PSM-21 137 0.94 6.5 0.87 25 21 — 1.51 203 PSM-11  830.50 5.0 0.50 11 11 — 1.62 185 PSM-A^(h,i) 285 0.96  0.3^(g) 0.53 37 38— 1.61 — PSM-B^(h) 229 0.53 1.5 0.33 22 20 — 1.73 — PSM-C 120  0.92^(j)2.8 0.56 16 17 — 1.61 — PSM-D 131  0.52^(j) 9.0 0.86 23 21 — 1.47 —P(VES) 229 0.94 5.5 0.82 39 36 35, 52 1.45 (1.50^(e)) 159 P(CES) 2310.94 5.5 0.78 37 32 35, 47 1.38 (1.32^(e)) 154 P(ES) 231 0.94 5.5 0.7636 33 36, 46 1.32 (1.30^(e)) 114 ^(a)The homopolymers labeled by numbersand heteropolymers were synthesized at 72° C. in anisole with 5 wt-%N,N-dimethylformamide as an internal standard and with an initiator (I,2,2′-azobisisobutyronitrile [AIBN]) to chain-transfer agent (C,2-cyano-2-propylbenzodithioate) ratio of 0.155 ± 0.005 mol/mol. Polymerslabeled by letters deviated from this procedure as indicated viasuperscripts h, i, and j. ^(b)Abbreviations stand for monomer (M) andsolvent (S). ^(c)See below for equation. ^(d)Determined relative topolystyrene standards using data from SEC with refractive-index (RI)detectors and a chloroform eluent. ^(e)Determined by Zimm analysis usingdata from SEC with a tetrahydrofuran (THF) eluent and light-scattering(LS) detectors. ^(f)For comparison, a PSM prepared by free-radicalpolymerization had a Ð of 2.65, and PSMs prepared with an ineffectivechain-transfer agent had Ð's of 2.14 and 2.39. ^(g)Reaction vitrified.^(h)Reaction temperature was 90° C. ^(i)[I]₀/[C]₀ = 0.32 ± 0.05 mol/mol.^(j)Solvent was chlorobenzene. $\begin{matrix}{M_{n,{calc}} = {\frac{\lbrack M\rbrack_{0} \cdot x \cdot M_{monomer}}{{\lbrack C\rbrack_{0} \cdot \left( {1 - \left( {1 - x} \right)^{C_{{tr},{app}}}} \right)} + {d \cdot f \cdot \lbrack I\rbrack_{0} \cdot \left( {1 - e^{{- k_{d}} \cdot t}} \right)}} + M_{C}}} & ({S1})\end{matrix}$

M_(monomer) (compositional average of the monomer molecular weights)=

-   -   222 g/mol for PSM syntheses    -   221 g/mol for P(VES) synthesis    -   219 g/mol for P(CES) synthesis    -   220 g/mol for P(ES synthesis

M_(c) (molecular weight of C)=221 g/mol.

f (Initiation efficiency of I)=0.5 (Moad et al. “Living RadicalPolymerization by the RAFT Process.” Aust. J. Chem. 2005, 58(6),379-410).

k_(d) (decomposition rate of I)≈5.7×10⁻⁵ s⁻¹ at 72° C. or 5.4×10⁻⁴ s⁻¹at 90° C. (AkzoNobel Product Data Sheet: Perkadox® AIBN. AkzoNobelPolymerChemistry: Amersfoort, The Netherlands, 2015).

d (number of chains produced in a methyl methacrylate-likeradical-radical termination event)=1.67 (Moad et al. “Living RadicalPolymerization by the RAFT Process.” Aust. J. Chem. 2005, 58(6),379-410).

C_(tr,app) (apparent chain-transfer coefficient) was approximately 2.6for hardwood and softwood monomers polymerized under the reactionconditions described herein. C_(tr,app) was assumed to be approximately2.6 for reactions performed under different conditions (the PSMs labeledby letters, which either had S=chlorobenzene or a reaction temperatureof 90° C.), noting that this factor affects M_(n,calc) by <1% for PSM-Cand PSM-D but could cause M_(n,calc) to be overestimated by up to 14%for PSM-A, 34% for PSM-B, and 11% for PSM-C.

Equation S1 accounts for chains initiated by free radicals and theapproximate time-dependent consumption of chain-transfer agent. Thecorresponding equation for the maximum number-average degree ofpolymerization (X_(n,max)) assumes 100% consumption of thechain-transfer agent at all conversions, no chains initiated by freeradicals, and no contribution of M_(C).

Equipment

¹H NMR data were collected and analyzed following a previously reportedmethodology (Holmberg et al., Softwood Lignin-Based MethacrylatePolymers with Tunable Thermal and Viscoelastic Properties.Macromolecules 2016, 49(4), 1286-1295). SEC data for the PSMhomopolymers and heteropolymers (relative to polystyrene standards) weredetermined on an Agilent HP 1100 instrument with chloroform as theeluent (1.0 mL/min, HP 1047A RI Detector, Carian PLgel Mixed-C columnsin series). Additional SEC data with light-scattering were determinedfor the heteropolymers using a Viscotek VE 3580 instrument withtetrahydrofuran (THF) as the eluent (1.0 mL/min; Viscotek VE3580 RI,UV-PDA, and Viscotek 270 Dual detectors; Waters Styragel HR1 and HR4columns [7.8×300 mm] in series). Analogous light-scattering SECexperiments were not performed on the PSM homopolymers due to their poorsolubility in THF.

Thermogravimetric analysis (TGA, 10° C./min under airflow), differentialscanning calorimetry (DSC, 5° C./min under air), and dynamic mechanicalanalysis (DMA) data were collected and analyzed as described in theliterature (Holmberg et al., Softwood Lignin-Based Methacrylate Polymerswith Tunable Thermal and Viscoelastic Properties. Macromolecules 2016,49(4), 1286-1295) to facilitate comparisons to softwood lignin-basedpolymers, but with minor differences indicated as follows. Temperaturewindows for DSC analysis [40-180° C. for PEM; 60-180° C. for P(ES);60-190° C. for P(CES) and P(VES); and 140-240° C. for PSM] were chosento minimize end-group thermolysis while also generating an above-T₉baseline of at least 20° C. to facilitate analysis. Samples for DMA (0.3mm in thickness, 8 mm in diameter) were prepared by pressing polymerpowder at high temperature [150° C. for P(ES); 190° C. for P(CES) andP(VES); and 240° C. for PSM-21] and pressure (1 metric ton) for 15 min.Frequency sweeps were taken at 10° C. temperature intervals, beginningnear the T_(g) and ending either when the polymer flowed out frombetween the parallel plates or slightly below the thermal degradationonset. Temperature sweeps were taken at 3° C./min at a frequency of 6.28rad/s. Strain amplitudes [frequency sweep: 0.1-5% for P(ES), 0.06-5% forP(CES), 0.1-5% for P(VES), and 0.2-1% for PSM-21; temperature sweep:0.05-5% for P(ES), 0.04-5% for P(CES), 0.06-5% for P(VES), and 0.1-1.5%for PSM-21] were varied to keep within the linear regime. Data wereshifted to a reference temperature of 180° C. (the maximum temperaturebefore polymer flow) for P(ES) and 220° C. (the only overlappingtemperature) for all other macromolecules using time-temperaturesuperposition.

Table S2 shows selected characteristics of the syringylmethacrylate-containing heteropolymers.

TABLE S2 Selected characteristics of SM-containing heteropolymers tofacilitate comparison^(a) P(ES) P(CES) P(VES) k_(p, app) ^(b) (h⁻¹) 0.23 ± 0.01  0.26 ± 0.02  0.26 ± 0.02 C_(tr, app) ^(c)  3.0 ± 0.3  2.5± 0.3  2.3 ± 0.7 T_(g,calc) ^(d) (° C.) 114 ± 3 153 ± 3 162 ± 3T_(g,meas) ^(e) (° C.) 114 ± 1 154 ± 1 159 ± 1 T_(o) ^(f) (° C.) 256 ± 5264 ± 5 260 ± 5 η₀ ^(g) (kPa · s) 0.2^(h) 37 39 ^(a)Values reported with95% confidence intervals if available. ^(b)Apparent propagation ratenormalized to an initiator-to-chain-transfer ratio of 0.100.^(c)Apparent chain-transfer coefficient determined using the Mayoequation and the change in dispersity at low conversions. ^(d)T_(g)calculated using the Fox equation and T_(g)'s of similar molecularweight homopolymers (130° C. for PVM, 110° C. for PEM, 126° C. for PCM,and 205° C. for PSM).⁸ ^(e)Average T_(g) from the midpoint of theinflection in the second and third heat of the DSC data (5° C./min).^(f)Onset degradation temperature determined in air using TGA (10°C./min). ^(g)Zero-shear viscosity at 220° C. determined by the Cox-Merzrule. ^(h)Value extrapolated from data collected at 160-180° C. assumingArrhenius behavior.

The polymerization rate and reactivity of syringyl methacrylate werefound to be consistent with the polymerization rates and reactivities ofsoftwood lignin-based monomers (EM, CM, VM and guaiacyl methacrylate(CM), despite the presence of a second methoxy group ortho to themethacrylate substituent in syringyl methacrylate (SM). k_(p,app)'s weredetermined to be the same at 95% confidence regardless of SM content andcompare favorably to the k_(p,app)'s reported for the softwoodlignin-based monomers (see Table S2). The compositions of the monomermixtures and the cumulative compositions of the heteropolymer changesalso do not change measurably with respect to conversion [x], furtherindicating the similar reactivities of the hardwood and softwoodlignin-based monomers and the likely random distributions of monomersegments in each chain. Consequently, syringol and guaiacol contents ina mixture can be manipulated without harming the predictability ofconversions, monomer distributions and molecular weight.

Control over the RAFT polymerizations also is consistent betweenguaiacylic and syringylic monomers, simplifying the process of tailoringmacromolecular characteristics. First, the dispersities decrease withrespect to increasing monomer conversion [x] and the normalized degreesof polymerization (X_(n)/X_(n,max)'s) change linearly with x, indicatingthat the polymerizations are controlled. Second, the size-exclusionchromatography (SEC) data are unimodal and the dispersities (alsoreferred to as polydispersities) of the homopolymers and heteropolymers(1.32-1.74) are similar to or better (lower) than what has beenpreviously reported for PVMs that were successfully chain-extended togenerate self-assembling block copolymers. Finally, the dispersities andX_(n)/X_(n,max)'s for the homopolymers and heteropolymers change withrespect to x in an approximately equivalent manner, albeit slightlyshifted vertically due to differences in polymer solubility. Theconsistency of these data was confirmed by estimating the C_(tr,app)from the heteropolymerizations using the Mayo equation. The resultingC_(tr,app)'s for the heteropolymers were within error of values reportedfor the polymerizations of GM, EM, CM, VM and corresponding mixtures.Additionally, C_(tr,app) for SM homopolymerizations is approximately thesame as for softwood lignin-based monomer polymerizations, furtherestablishing that the presence of the second o-methoxy group in SM has asurprisingly negligible effect on its polymerization behavior.

PSM-24 has a larger dispersity in part because the reaction mixturegelled. The lower dispersities listed in Table S1 were achieved bydiluting the reaction mixture, reducing the target molecular weight,changing the solvent and incorporating softwood lignin-basedmethacrylate monomers. All of these changes contribute to reductions insolution viscosity and thus polymer dispersity.

The measured T_(g)'s of the PSM homopolymers (185-205° C. depending onmolecular weight, see also Table S1) are among the highest reported foramorphous, linear polymers with aliphatic backbones, even greater thanthe T_(g)'s reported for poly(2,6-dimethylphenyl methacrylate (189° C.)and poly(2,6-diisopropylphenyl methacrylate (198° C.). A PSM of infinitemolecular weight could have a T_(g) as high as about 220° C., assumingFlory-Fox behavior when fitting data from Table S1. The T_(g) of PSM-24is about 75° C. higher than that of PVM and about 95° C. higher thanthat of PEM at similar number average molecular weight.

Syringyl methacrylate segments also can be incorporated into polymers tomake predictable changes to the T_(g) based on composition and the Foxequation. The actual and calculated Fox-based T_(g)'s were found toagree closely. For example, incorporating 5 wt % of SM segments into PEMraises the T_(g) by 4° C. (from 110° C. to 114° C.), the predictedincrease. The heteropolymers with compositions that mimic possiblefractions of bio-oil (f_(SM)=0.48-0.55) were found to have similarlypredictable, yet high (154° C. and 159° C.) glass transitiontemperatures. Furthermore, the onset thermal degradation temperatures inair for PSM (303±5° C.) and the heteropolymers (256-260° C.) are about100° C. greater than each of the measured T_(g)'s; thus, these polymerscan be melt-processed without significant thermal degradation.

The η₀'s for SM-containing polymers were found to span about 5 orders ofmagnitude and to depend largely on the SM content. For example, the η₀at 220° C. is 17,000 k.Pas for PSM and significantly less for theSM-containing heteropolymers listed in Table S2. This window of η₀'s issubstantial in comparison to the approximately 2 orders of magnitudespanned by the complete range of guaiacylic methacrylate polymers andcould be even wider if higher molecular weight polymers, relative toPSM-24, were examined. Thus the use of syringyl methacrylate as amonomer provides a much wider space over which processability anddeformation resistance can be optimized.

In summary, no other system of biobased monomers allows polymer T_(g)'sfrom about 100° C. (ideal for thermoformable, yet boiling water-stable,plastics, such as cups) to about 200° C. (ideal for heat- andflow-resistant materials, such as asphalt binders) to be accessed asreadily as the dimethoxyphenol-based monomers described herein. Themeasurable changes in T_(g) and η₀ at low content of SM, and thewide-ranging thermomechanical properties attainable through thedimethoxyphenol-based polymers of the present invention confirm thatsuch monomers (e.g., syringyl methacrylate) are powerful add-in monomersfor adjusting material properties. The similar polymerizationcharacteristics between the dimethoxyphenol-based monomers of thepresent invention and other types of lignin-based monomers (inparticular, monomers derived from softwood lignin) also greatly simplifythe task of predicting a priori the macromolecular characteristics andproperties of any heteropolymer containing dimethoxyphenol andsyringylic segments. Hence, syringyl methacrylate, as well as the otherdimethoxyphenol-based monomers described herein, is a biobased monomerextraordinarily capable of significantly raising polymer T_(g)'s anddeformation resistances at comparatively low levels in polymers.

The successful synthesis and isolation of syringol methacrylate wassomewhat unexpected, mainly because syringol tends to favor conversionto stable phenoxy radicals and colored quinones. The discovery thatsyringyl methacrylate can be successfully polymerized using RAFTpolymerization also was somewhat unexpected, in view of the presence ofo-methoxy groups in the monomer. Other poly(phenyl methacrylate)derivatives with bulky o-groups can be challenging to synthesize due tolow ceiling temperatures and polymer thermal stabilities.

The polymerization rate and reactivity of syringol methacrylate werefound to be consistent with the polymerization rate and reactivity ofmonomers derived from softwood lignin (EM, CM, VM and guaiacylmethacrylate [GM]), despite the presence of a second o-methoxy group inthe syringyl methacrylate. The k_(p,app) values observed were the sameat 95% confidence regardless of SM content and compare favorably to thek_(p,app)'s previously for softwood monomers. The compositions of themonomer mixtures and the cumulative compositions of the heteropolymerchains also do not change measurably with respect to conversion, furtherindicating the similar reactivities of the hardwood (syringol-based) andsoftwood monomers and the likely random distributions of monomersegments in each chain. Consequently, the relative content ofdimethoxyphenol-based monomer and guaiacol-based monomer in apolymerization mixture can be manipulated without harming thepredictability of conversions, monomer distributions and molecularweight.

What is claimed is:
 1. A polymer comprising, in polymerized form, atleast one polymerizable monomer comprised of a phenyl ring, two methoxygroups substituted on the phenyl ring, and at least one substituent onthe phenyl ring comprised of at least one polymerizable functional groupwhich is an ethylenically unsaturated functional group, wherein theethylenically unsaturated functional group has been polymerized in thepolymer, wherein the at least one polymerizable monomer has a structurecorresponding to formula (I):

wherein R1 is a heteroatom-containing organic moiety selected from thegroup consisting of aldehyde-containing groups, ketone-containinggroups, carboxylic acid-containing groups, and hydroxyl-containinggroups; and wherein R2 is the substituent comprised of at least onepolymerizable functional group which is an ethylenically unsaturatedfunctional group.
 2. The polymer of claim 1 additionally comprising, inpolymerized form, one or more polymerizable co-monomers other thanpolymerizable monomers having structures corresponding to formula (I).3. The polymer of claim 2, wherein the one or more polymerizableco-monomers are selected from the group consisting of lignin-basedmonomers, styrenes, phenyl [meth]acrylates, alkyl [meth]acrylates,[meth]acrylates other than alkyl [meth]acrylates and phenyl[meth]acrylates, terephthalates, amides, amines, diamides, diamines,dichlorides, nitriles, carboxylic acids, lactones, lactams, maleates,fumarates, malonates, maleinates, vinyls, vinyl esters, vinyl amides,[meth]acrylamides, thiols, dithiols, polythiols, enes, dienes, olefins,allyl monomers, azides, diazides, phosgene, carbonates, carbamates,succinates, alcohols, silanes, silicones, siloxanes, ethers, vinylethers, vinyl sulfides, isocyanates, epoxides, norbornenes, anhydrides,and combinations thereof.
 4. The polymer of claim 2, wherein the polymeris a block copolymer, random copolymer, star polymer, brush polymer, orgradient copolymer.
 5. A polymer comprising, in polymerized form, atleast one polymerizable monomer comprised of a phenyl ring, two methoxygroups substituted on the phenyl ring, and at least one substituent onthe phenyl ring comprised of at least one polymerizable functional groupwhich is an ethylenically unsaturated functional group, wherein theethylenically unsaturated functional group has been polymerized in thepolymer, wherein the at least one polymerizable monomer has a structurecorresponding to formula (I):

wherein R₁ is hydrogen or formyl and R₂ is [meth]acrylate.
 6. Thepolymer of claim 5 additionally comprising, in polymerized form, one ormore polymerizable co-monomers other than polymerizable monomers havingstructures corresponding to formula (I).
 7. The polymer of claim 6,wherein the one or more polymerizable co-monomers are selected from thegroup consisting of lignin-based monomers, styrenes, phenyl[meth]acrylates, alkyl [meth]acrylates, [meth]acrylates other than alkyl[meth]acrylates and phenyl [meth]acrylates, terephthalates, amides,amines, diamides, diamines, dichlorides, nitriles, carboxylic acids,lactones, lactams, maleates, fumarates, malonates, maleinates, vinyls,vinyl esters, vinyl amides, [meth]acrylamides, thiols, dithiols,polythiols, enes, dienes, olefins, allyl monomers, azides, diazides,phosgene, carbonates, carbamates, succinates, alcohols, silanes,silicones, siloxanes, ethers, vinyl ethers, vinyl sulfides, isocyanates,epoxides, norbornenes, anhydrides, and combinations thereof.
 8. Thepolymer of claim 6, wherein the polymer is a block copolymer, randomcopolymer, star polymer, brush polymer, or gradient copolymer.